Three-Dimensional Shape Detecting Device, Image Capturing Device, and Three-Dimensional Shape Detecting Program

1. A three-dimensional shape detecting device comprising a projection unit which projects pattern light, an image capturing unit which captures a pattern light projection image of a subject on which the pattern light is projected, and a three-dimensional shape calculation unit which calculates a three-dimensional shape of the subject based on a locus of the pattern light extracted from the pattern light projection image captured by the image capturing unit, wherein the three-dimensional shape detecting device further comprises: a first area setting unit which sets a first area, including a first portion of the locus of the pattern light extending in an X-axis direction of the pattern light projection image, in the pattern light projection image; a first detecting unit which detects a plurality of pixels forming the first portion of the locus of the pattern light in the first area set by the first area setting unit; an approximated curve calculation unit which calculates an approximated curve regarding the first portion of the locus of the pattern light based on the plurality of pixels detected by the first detecting unit; and a second area setting unit which sets a second area for detecting pixels forming a second portion of the locus of the pattern light in the pattern light projection image, based on the approximated curve calculated by the approximated curve calculation unit, wherein the extracted locus of the pattern light is based on the plurality of pixels detected by the first detecting unit and the pixels detected in the second area set by the second area setting unit and wherein the three-dimensional shape of the subject is based on the extracted locus.

2. The three-dimensional shape detecting device according to claim 1 , wherein the first area setting unit sets an area in the pattern light projection image including a central part of the locus of the pattern light as the first area including the first portion of the locus of the pattern light.

3. The three-dimensional shape detecting device according to claim 1 , further comprising: a detecting position setting unit which sets a plurality of detecting positions in the X-axis direction of the pattern light projection image for detecting the pixels forming the second portion of the locus of the pattern light, from a position outside the first area toward an edge part of the pattern light projection image; a second detecting unit which detects the pixels forming the second portion of the locus of the pattern light at each of the detecting positions set by the detecting position setting unit; and a first update unit which updates the approximated curve calculated by the approximated curve calculation unit, in regard to each pixel detected by the second detecting unit based on the pixel and the plurality of pixels detected by the first detecting unit, wherein: the second area setting unit restricts a range in a Y-axis direction of the pattern light projection image at each of the detecting positions set by the detecting position setting unit, and the range in the Y-axis direction is restricted based on the approximated curve calculated by the approximated curve calculation unit at a detecting position first set by the detecting position setting unit, while being restricted based on the approximated curve updated by the first update unit at detecting positions set subsequently.

4. The three-dimensional shape detecting device according to claim 3 , wherein the detecting position setting unit sets the detecting positions alternately in two areas on both sides of the first area.

5. The three-dimensional shape detecting device according to claim 3 , further comprising: a counter which counts the number of times for which no pixel is detected by the second detecting unit at each detecting position; a judgment unit which judges whether or not the number of times counted by the counter exceeds a prescribed number of times at consecutive detecting positions; and a stopping unit which stops the detection by the second detecting unit at subsequent detecting positions when the judgment unit judges that the number of times counted by the counter exceeds the prescribed number of times at consecutive detecting positions.

6. The three-dimensional shape detecting device according to claim 5 , further comprising: an extracting unit which extracts pixels that are a prescribed distance or more apart from the approximated curve calculated by the approximated curve calculation unit in the Y-axis direction of the pattern light projection image from the plurality of pixels detected by the first detecting unit, wherein: the extracted locus of the pattern light is based on the plurality of pixels detected by the first detecting unit, excluding the pixels extracted by the extracting unit, and the pixels detected in the second area set by the second area setting unit.

7. The three-dimensional shape detecting device according to claim 6 , further comprising a second update unit which updates the approximated curve calculated by the approximated curve calculation unit based on the plurality of pixels detected by the first detecting unit excluding the pixels extracted by the extracting unit, wherein: the second area setting unit restricts the range in the Y-axis direction at the detecting position first set by the detecting position setting unit based on the approximated curve updated by the second update unit.

8. The three-dimensional shape detecting device according to claim 7 , wherein the first and second update units calculate the approximated curve gradually increasing the degree of the approximated curve.

9. An image capturing device comprising: the three-dimensional shape detecting device according to claim 1 ; and a plane image correction unit which corrects a pattern light non-projection image of a subject, captured by the image capturing unit of the three-dimensional shape detecting device with no pattern light projected on the subject, to a plane image viewing the subject from a direction substantially orthogonal to a prescribed surface of the subject based on the three-dimensional shape of the subject calculated by the three-dimensional shape calculation unit of the three-dimensional shape detecting device.

10. A computer program embodied on a computer-readable medium for calculating a three-dimensional shape of a subject based on a locus of pattern light extracted from a pattern light projection image of the subject captured with pattern light projected on the subject, the computer program product comprising computer-readable instructions that cause a computer to execute: a first area setting program segment for setting a first area, including a first portion of the locus of the pattern light, in the pattern light projection image; a first detecting program segment for detecting pixels forming the first portion of the locus of the pattern light in the first area set by the first area setting program segment; an approximated curve calculation program segment for calculating an approximated curve regarding the first portion of the locus of the pattern light based on the pixels detected by the first detecting program segment; and a second area setting program segment for setting a second area for detecting pixels forming a second portion of the locus of the pattern light in the pattern light projection image, based on the approximated curve calculated by the approximated curve calculation program segment, wherein: the extracted locus of the pattern light is based on the pixels detected by the first detecting program segment and the pixels detected in the second area set by the second area setting program segment and the three-dimensional shape of the subject is based on the extracted locus.

11. A computerized method for calculating a three-dimensional shape of a subject based on a locus of pattern light extracted from a pattern light projection image of the subject captured with pattern light projected on the subject, the method comprising: setting a first area, including a first portion of the locus of the pattern light in the pattern light projection image; detecting pixels forming the first portion of the locus of the pattern light in the first area set in the first area setting step; calculating an approximated curve regarding the first portion of the locus of the pattern light based on the pixels detected in the detecting step; and setting a second area, including a second portion of the locus of the pattern light in the pattern light projection image, based on the approximated curve calculated in the approximated curve calculation step; detecting pixels forming the second portion of the locus of the pattern light in the second area set in the second area setting step, wherein: the extracted locus of the pattern light is based on the pixels detected in the detecting step and the pixels detected in the second area set in the second area setting step and the three-dimensional shape of the subject is based on the extracted locus.